This entire question is completely distorted by the poor-qualtiy postwar urbanism that is rampant everywhere.

The reality is, there shouldn't be much difference. Lowrise cities -- 2-4 story buildings/townhomes, small apartments, walkable neighborhoods/mass transit, corner groceries, all that stuff that people think can ONLY exist in big cities should be the norm for nearly all towns.

I don't think many people would describe a place like, say, Bordeaux as a "big city". 250kish people in 50 square kilometers is hardly Paris. It's a small city, or maybe a big town. And it has everything you can want from a city and more. Shows, museums, beautiful multimodal neighborhoods, a robust tram system, restaurants and cafes and bars. All this kind of stuff.

The problem is we've all been mentally taught you can either live in island, R1A zoned suburbs which require driving to do ANYTHING or else you need to live in a huge metropolis like NYC. Or else we've been trained to think of a "city" like the bullshit they have in Texas, where it combines all the worst features of those island suburbs/car dependence with all the worst parts of city (crazy prices, noise, exposure to nearby-feeling crime, etc).

While a lot of the US big cities are trying to sort out the knots they've tied themselves in, your best bet to find beautiful, livable urban-ism is in those much smaller <500k cities that don't even show up on the typical lists of cities. Especially if they are historic, since the more historic a place is the less likely it got bulldozed in the 60s to make room for more highways (destroying local neighborhoods in the process) Some kind of a big university also tends to be a plus, though it's a mixed bag. Check for places that do not have an interstate carving through the middle of the city.

We can only get the amenities of modern urbanism in the biggest metropolises these days because of how badly the "suburban experiment" has distorted and destroyed our community life. And there can only be so many metropolises, so they've naturally turned absurdly expensive. People can't afford to live in them because of how much people want to live in them. So they settle for suburbia, since financial poverty feels way worse than poverty of community.